In general terms, this invention relates to an anti-theft system where a remote signaling device, which can be mounted on a key for example, communicates with a system controller only under prescribed conditions.
Vehicle theft is a common and widespread problem. A variety of anti-theft systems have been developed and are commercially available. Typical systems include a remote signaling device that communicates with the anti-theft system mounted on the vehicle. In conventional systems, there is only one-way communication provided from the remote signaling device to the anti-theft system mounted on the vehicle. A variety of measures have been proposed to prevent sabotage or overriding the security of an anti-theft system. One such proposal includes using coded or encrypted communication signals from the remote device to the controller on the vehicle. Such solutions have not proven completely successful, however.
One possible way that the vehicle security systems are overridden is for a thief to use a signal capturing device to monitor a signal transferred from a remote device to a controller on a vehicle. By monitoring such signals, the thief can mimic or imitate the coded signal from the remote signaling device and, therefore, operate the vehicle security system in a manner that allows the thief to steal the vehicle.
A proposed solution to the above problem is to provide varying, encrypted signals from the remote device to the controller. These measures can prove prohibitively expensive when the remote device must contain sufficient memory for generating a varying signal. Further, even in situations where the remote device generates a varying signal, mathematical algorithms or multiple sampling schemes can be used to essentially break the code and disable the anti-theft system.
This invention addresses the needs and shortcomings of the systems discussed above. This invention provides a secure method of communicating between a remote device and a controller on a vehicle for operating an anti-theft system.